It is necessary and also common in most cases that the conduit for supplying either syrup or concentrate be associated with a non-return valve. This measure is necessary in order to prevent water or mixed beverage from entering the supply conduit upon the occurrence of a malfunction. Such non-return valve is also required because the mixing chamber and all of the parts of the system contacting the mixed beverage must be rinsed and cleaned with water for reasons of hygiene.
For this purpose, a controlled connection for pressurized water is known to be provided between the mixing chamber and the non-return valve to open for rinsing purposes when the supply conduit leading to the water jet pipe is closed. It is also possible to separate the non-return valve and the associated connection for syrup and concentrate from the injector housing and bring the connection of the injector housing into communication with a rinsing conduit.
All of these solutions are time-consuming and complicated and difficult in operation. As a consequence of the high operational expenditure, the system suffers from the danger of being not rinsed in sufficient short time intervals and thus hygienic problems may result.